The food stuffs casing according to the present invention is a further development of the polyamide sausage casing described in DE-PS 28 50 181, DE-PS 28 50 182, and DE-PS 32 27 945. Express reference is made to the patents described above. In these known casings, what is involved is a shrinkably stretched casing (DE-PS 181 and 182), or a casing that will not shrink since it is completely fixed thermally (DE-PS 945). Experience gained in the daily use and production of the successfully marketed food stuffs casings according to the above quoted patents has shown that they can be improved from the point of view of use both with regard to manufacture and to use itself.
Developments with regard to production of these casings relate to gathering and closing the casings on one side, whereas improvement with regard to application relates to avoiding processing errors with the most simple handling and this results in a significant improvement in the appearance of the product.
It is the state-of-the-art that all formerly known food stuffs casings, even those that have been improved according to the present invention, can only be shirred and yet remain undestroyed by the use of hydrophobic tightening lubricating agents, i.e., can be shirred free of any holes. Triglyceride mixtures are particularly well suited as lubricating agents that are suitable for food stuffs. As a rule, these oils are applied immediately before shirring to the shirring machine with the casing that is to be shirred.
In order that there is no negative effect in the adhesion of the sausage filling to the casing it is known that shirring lubricating agents can, as a rule, be sprayed onto the outer surface of the food stuffs casing during the shirring process using commercially conventional shirring machinery.
This process entails considerable disadvantages when used for cases according to DE-PS 28 50 181, DE-PS 28 50 182 and DE-PS 32 27 945:
The shirring lubricating agent that is applied to the exterior of the food stuffs casing wets both the surface of the casing and the shirring rollers and thus reduces friction and then, because the shirring rollers cannot move the inflated casings forward, causes a build-up on the shirring rod.
For this reason, the shirring rollers will then rotate on the same piece of casing and will heat the casing and the shirring agent such that tightening holes will result and/or the print or printing edge will be smeared.
Within certain limits varying amounts of lubricating agent on the casing surface are technically unavoidable. This results in unacceptably high differences in diameter when the casing are filled with sausage meat, for example, using conventional filling and clipping machinery having stop-lips that operate on the exterior.
The hydrophobic shirring lubricating agents make it more difficult to wet the surface of the casing with water and because of this the fundamental moistening of the casing in place. Non-homogenous or insufficiently watered casings according to DE-PS 28 50 181, DE-PS 28 50 182 and DE-PS 32 27 945 are, however, unuseable for filling because their special shrinkage and elasticity characteristics are only activated when they are saturated with water. It is not possible to fill insufficiently wetted casings so as to provide a constant diameter at the prescribed minimum. Creased and/or unequal end products are as a rule returned for such deficiencies. They are not wanted because they reduce the marketable value of the end product. The further processing of sausage goods with very varied diameters is not possible for packing when sliced because the weight of the individual slices varies too greatly.
Tightening lubricating agents are also effective as separating agents. They make it more difficult to apply labels to the finished product.
Food stuff casings according to the above cited patent specifications are normally made up into single casings of varying length which are tied off and clipped at one end. To this end, in the folding station or a conventional tying-off machine they are passed by a pair of rollers having intermeshing teeth, and thus laid up into folds and picked up by a gripper to be fixed in the folded state and then passed on the clipping and tying station. When passed to the gripper the creases in the casing open out and thus make it extremely difficult to position the clipping and tying knots accurately. It frequently happens that the clip will drill into the creases that have been opened out or will at least be crooked.
All of the deficiencies in production are causes for breakdowns in the production process. Thus, it is the principle objective of the present invention to avoid these disadvantages.
End products that are of varying diameters caused by different quantities of tightening lubricating agent on the gut and as a consequence of inadequate wetting with water when in place have already been addressed.
The avoidance of end products having greatly differing diameters is also an objective of the present invention from the point of view of application technology. The further objective of development from the application point of view is the avoidance or the minimizing of tightening folds in the end product.
It is already known that tightening of food stuffs casings that are being discussed, in particular, according to DE-PS 32 27 945 according to the state-of-the-art, which is to say in air dried condition and by the use of shirring lubricating agents, causes a sharply impressed shirring lubricating agents, causes a sharply impressed tightening fold in the casing. Even after the casing has been filled with sausage meat during a 10% diameter expansion and even after heat treatment of the filling during further lateral expansion, it is still impossible to smooth out these creases.
It is the object of the present invention to so improve the foils used for casings as in DE-PS 28 50 181, DE-PS 28 50 182 and DE-PS 32 27 945 to the point that they can be made up without any problems, i.e., without the use of an additional tightening lubricating agent and so tightened that the casings can be filled to a constant diameter and the casings can be tied off and clipped without error and without any loss and so that the filled casings display no visible tightening folds.